Free lab and Act I · no account needed
Build a CPU from the transistor up
Build gates, memory, and a working 8-bit CPU from CMOS transistors in your browser. Learn step by step, with an optional AI circuit tutor.
A live XOR gate. Open the lab and build your own →Build digital circuits
Open the free sandbox. Drag transistors and gates, wire them up, flip a switch and watch the logic light up. No account needed.
Open the labLearn to build a CPU
Learn by building. 40+ hands-on levels carry you from a single transistor to a working CPU, then you write programs for it, checked step by step.
Start the courseExplore digital logic
The concepts, answer-first: gates, Boolean algebra, adders, memory, and CPUs, each with a playable diagram you can open in the lab.
Explore the lessonsFrom switches to a computer you can program
Wire NMOS and PMOS transistors into logic gates, combine gates into adders and memory, then assemble an 8-bit CPU. The switch-level simulator resolves your circuit’s signals; course checks verify each build before you move on. Playable theory diagrams use the same engine and open directly in the lab.
Created and maintained by Taceddin Sancak in Türkiye, a project from wleeaf. Read how the simulator is built →
Or just watch it work
Six quick, hands-on walkthroughs, from one transistor up to a running CPU. No account, no commitment: click and watch.